From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa1-x2b.google.com (mail-oa1-x2b.google.com [IPv6:2001:4860:4864:20::2b]) by sourceware.org (Postfix) with ESMTPS id A32CD3852C41; Thu, 24 Nov 2022 00:23:18 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org A32CD3852C41 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-oa1-x2b.google.com with SMTP id 586e51a60fabf-142faa7a207so295432fac.13; Wed, 23 Nov 2022 16:23:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=QcRFv12hKM8S0ARNwQfKfMw7p0xSu2IrgCHiwUz/ClM=; b=DHb7vuC9vH62W0w6XSoll+k0kHftA+W2uErXvl7wxQE93Q+Mv0FRoKuO6tp/x5BwqA 9gw3IojDyo0Elwy3wrI3dVljewZXSQ1SE7EQ1BBs5Wh1cSB5y8P4MndgoI7Qb6CKMu2S URTtDf1bwpDrIFqrAv66fNfC51EeicoaGgxNKl+dC/p57xKrWMi01JgleOgFXZyYDSzT McPCe5JIDyBZheBfn4xtmHOxZTNpB0yDKOe11PIYPAwNOTVWfdycEOE0jq4OC70lIBw8 8hvUk8XQeRPrBW/inIpXPKSOO8RW26Vu3jsnx00CG+z8Jt6z3pl4V2JOSOs6Mrs9Zs5D tYlQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=QcRFv12hKM8S0ARNwQfKfMw7p0xSu2IrgCHiwUz/ClM=; b=YhrVS5vo0D+cvfrn/u7ijTZ5avUkMkwqTt/cu4n4fIW11DNDrujNr8FlJlbNPoOBYg gn9+BAoWKGiaqarFaexYpb87q/X0WCWbEMIa6ZFWdSZ4QzzXG7WWAEEwpMaHDCqPG+5o 5WI09A565JLl4ohsY49sMMxCVzd2gGpZ1gSxhh/YOzquZvIAE2iVxmmOahCAze2kB9AS 0GBg9jWYkwL4Oht1zMGcxjvj4XxhWJPyN/CHp3sMvH/w51eHxWltucv8AqifeKmz71B2 J2xOZjkojreg9+lo7IxEhmIAsUBi8Q66zDp3cqG2iN3WS4fzu+siE776E9XMh5ZPmaDM d0tQ== X-Gm-Message-State: ANoB5pkPOP0rtT0JGcIb679z5k3hx/neQYLZ/cphIYfSEifeE5uT0Yu4 4+qUd48in/iEQ47ePU9zA5oJAPd+cM+ecZVCuXfo3dzz X-Google-Smtp-Source: AA0mqf44RVVNwAJLzCHY6P1BPNB/B+0tjea7bOiEqQhUJ85BetO7zwrBkXh0fOQd0CYk4bih1iDQc6CKGb5SGIYtjew= X-Received: by 2002:a05:6871:4501:b0:13c:5da4:7229 with SMTP id nj1-20020a056871450100b0013c5da47229mr11180607oab.266.1669249397657; Wed, 23 Nov 2022 16:23:17 -0800 (PST) MIME-Version: 1.0 References: <20220921005804.7131-1-goldstein.w.n@gmail.com> In-Reply-To: From: "H.J. Lu" Date: Wed, 23 Nov 2022 16:22:41 -0800 Message-ID: Subject: Re: [PATCH v1] x86: Fix wcsnlen-avx2 page cross length comparison [BZ #29591] To: Sunil Pandey Cc: Libc-stable Mailing List , Noah Goldstein , libc-alpha@sourceware.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-3023.3 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On Wed, Nov 23, 2022 at 2:21 PM Sunil Pandey wrote: > > On Wed, Sep 21, 2022 at 3:02 PM H.J. Lu via Libc-alpha > wrote: > > > > On Tue, Sep 20, 2022 at 5:58 PM Noah Goldstein wrote: > > > > > > Previous implementation was adjusting length (rsi) to match > > > bytes (eax), but since there is no bound to length this can cause > > > overflow. > > > > > > Fix is to just convert the byte-count (eax) to length by dividing by > > > sizeof (wchar_t) before the comparison. > > > > > > Full check passes on x86-64 and build succeeds w/ and w/o multiarch. > > > --- > > > string/test-strnlen.c | 70 +++++++++++++++----------- > > > sysdeps/x86_64/multiarch/strlen-avx2.S | 7 +-- > > > 2 files changed, 43 insertions(+), 34 deletions(-) > > > > > > diff --git a/string/test-strnlen.c b/string/test-strnlen.c > > > index 4a9375112a..5cbaf4b734 100644 > > > --- a/string/test-strnlen.c > > > +++ b/string/test-strnlen.c > > > @@ -73,7 +73,7 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char) > > > { > > > size_t i; > > > > > > - align &= 63; > > > + align &= (getpagesize () / sizeof (CHAR) - 1); > > > if ((align + len) * sizeof (CHAR) >= page_size) > > > return; > > > > > > @@ -90,38 +90,50 @@ do_test (size_t align, size_t len, size_t maxlen, int max_char) > > > static void > > > do_overflow_tests (void) > > > { > > > - size_t i, j, len; > > > + size_t i, j, al_idx, repeats, len; > > > const size_t one = 1; > > > uintptr_t buf_addr = (uintptr_t) buf1; > > > + const size_t alignments[] = { 0, 1, 7, 9, 31, 33, 63, 65, 95, 97, 127, 129 }; > > > > > > - for (i = 0; i < 750; ++i) > > > + for (al_idx = 0; al_idx < sizeof (alignments) / sizeof (alignments[0]); > > > + al_idx++) > > > { > > > - do_test (1, i, SIZE_MAX, BIG_CHAR); > > > - > > > - do_test (0, i, SIZE_MAX - i, BIG_CHAR); > > > - do_test (0, i, i - buf_addr, BIG_CHAR); > > > - do_test (0, i, -buf_addr - i, BIG_CHAR); > > > - do_test (0, i, SIZE_MAX - buf_addr - i, BIG_CHAR); > > > - do_test (0, i, SIZE_MAX - buf_addr + i, BIG_CHAR); > > > - > > > - len = 0; > > > - for (j = 8 * sizeof(size_t) - 1; j ; --j) > > > - { > > > - len |= one << j; > > > - do_test (0, i, len - i, BIG_CHAR); > > > - do_test (0, i, len + i, BIG_CHAR); > > > - do_test (0, i, len - buf_addr - i, BIG_CHAR); > > > - do_test (0, i, len - buf_addr + i, BIG_CHAR); > > > - > > > - do_test (0, i, ~len - i, BIG_CHAR); > > > - do_test (0, i, ~len + i, BIG_CHAR); > > > - do_test (0, i, ~len - buf_addr - i, BIG_CHAR); > > > - do_test (0, i, ~len - buf_addr + i, BIG_CHAR); > > > - > > > - do_test (0, i, -buf_addr, BIG_CHAR); > > > - do_test (0, i, j - buf_addr, BIG_CHAR); > > > - do_test (0, i, -buf_addr - j, BIG_CHAR); > > > - } > > > + for (repeats = 0; repeats < 2; ++repeats) > > > + { > > > + size_t align = repeats ? (getpagesize () - alignments[al_idx]) > > > + : alignments[al_idx]; > > > + align /= sizeof (CHAR); > > > + for (i = 0; i < 750; ++i) > > > + { > > > + do_test (align, i, SIZE_MAX, BIG_CHAR); > > > + > > > + do_test (align, i, SIZE_MAX - i, BIG_CHAR); > > > + do_test (align, i, i - buf_addr, BIG_CHAR); > > > + do_test (align, i, -buf_addr - i, BIG_CHAR); > > > + do_test (align, i, SIZE_MAX - buf_addr - i, BIG_CHAR); > > > + do_test (align, i, SIZE_MAX - buf_addr + i, BIG_CHAR); > > > + > > > + len = 0; > > > + for (j = 8 * sizeof (size_t) - 1; j; --j) > > > + { > > > + len |= one << j; > > > + do_test (align, i, len, BIG_CHAR); > > > + do_test (align, i, len - i, BIG_CHAR); > > > + do_test (align, i, len + i, BIG_CHAR); > > > + do_test (align, i, len - buf_addr - i, BIG_CHAR); > > > + do_test (align, i, len - buf_addr + i, BIG_CHAR); > > > + > > > + do_test (align, i, ~len - i, BIG_CHAR); > > > + do_test (align, i, ~len + i, BIG_CHAR); > > > + do_test (align, i, ~len - buf_addr - i, BIG_CHAR); > > > + do_test (align, i, ~len - buf_addr + i, BIG_CHAR); > > > + > > > + do_test (align, i, -buf_addr, BIG_CHAR); > > > + do_test (align, i, j - buf_addr, BIG_CHAR); > > > + do_test (align, i, -buf_addr - j, BIG_CHAR); > > > + } > > > + } > > > + } > > > } > > > } > > > > > > diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S > > > index 0593fb303b..b9b58ef599 100644 > > > --- a/sysdeps/x86_64/multiarch/strlen-avx2.S > > > +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S > > > @@ -544,14 +544,11 @@ L(return_vzeroupper): > > > L(cross_page_less_vec): > > > tzcntl %eax, %eax > > > # ifdef USE_AS_WCSLEN > > > - /* NB: Multiply length by 4 to get byte count. */ > > > - sall $2, %esi > > > + /* NB: Divide by 4 to convert from byte-count to length. */ > > > + shrl $2, %eax > > > # endif > > > cmpq %rax, %rsi > > > cmovb %esi, %eax > > > -# ifdef USE_AS_WCSLEN > > > - shrl $2, %eax > > > -# endif > > > VZEROUPPER_RETURN > > > # endif > > > > > > -- > > > 2.34.1 > > > > > > > LGTM. > > > > Thanks. > > > > -- > > H.J. > > I would like to backport this patch to affected release branches from > 2.36 to 2.33. > > Any comments/suggestions or objections on this. > OK. Thanks. -- H.J.